1. Field
The present invention relates to a robot and a method of controlling the same, and more particularly, to a method of generating a hip trajectory of a biped walking robot to allow the robot to stably walk on a two-dimensional space without falling down.
2. Description of the Related Art
In general, machines, which conduct motions similar to those of a human being using an electrical or magnetic action, are known as robots. Early robots were industrial robots, such as manipulators or transfer robots, for work automation and unmanned operation in a production field. These robots performed dangerous work, simple repetitive work, or work requiring large forces in place of a human being. Recently, biped walking robots have been vigorously researched and developed. The biped robots have a joint system similar to that of a human being, live together with the human being in human working and living spaces, and walk with two feet, have been vigorously researched and developed.
Methods of controlling the walking of a biped robot include a position-based zero moment point (ZMP) control method, and a torque-based finite state machine (FSM) control method. In the ZMP control method, values desired by a user on a rectangular coordinate system are generated in advance based on the center of gravity of the biped robot and ends (hereinafter, referred to as end effectors) of both feet of the robot, and desired trajectories of all joints of the robot are made using kinematics characteristics between links and the joints of the robot. Such a ZMP control method maps the desired rectangular coordinate trajectories of the end effectors in consideration of a weight-based ZMP trajectory with angles/angular velocities/accelerations of the joints, and thus requires a large amount of calculation in real time and has a complicated calculating process. Further, results of a calculation expression regarding all joints are obtained in a path, in which the robot will move, and plural solutions are calculated. Thus, a solution desired by a user should be obtained by simulation or checked again. On the other hand, in the FSM control method, finite states of the biped robot are defined in advance, and then the finite states of the biped robot are sequentially changed while walking, thus allowing the biped robot to properly walk. Thus, the FSM control method is capable of obtaining a stable walking pattern without using a complicated calculating process, when relationships between desired angles of joints are generated. Accordingly, the relationships between the desired angles of the respective joints should be set such that the biped robot can stably walk without falling down.